kevinthesun commented on a change in pull request #5020:
[Frontend][TensorFlow]TensorFlow Parser Control Flow Enhancement
URL: https://github.com/apache/incubator-tvm/pull/5020#discussion_r392375860
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File path: python/tvm/relay/frontend/tensorflow.py
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@@ -2029,6 +2096,73 @@ def if_node(self):
return self._if
+class LoopBound(ExprVisitor):
+ """
+ When a loop body is create, we get a Relay expression backtracing all
+ the way back to input node. This will result in lots of unnecessary
+ expression placed into loop body and compute multiple times. For example,
+ consider the following tensorflow code:
+
+ .. code-block:: python
+
+ i = tf.constant(0)
+ data = tf.compat.v1.placeholder(tf.float32, shape=(1024, 1024))
+ slice = tf.strided_slice(data, 0, 512)
+ def c(i): return tf.less(i, 10)
+ def b(i): return [tf.add(i, 1), tf.add(i, 1) + slice]
+ r = tf.while_loop(c, b, [i])
+
+ If we directly create recursive function, slice will be placed into
function body.
+ Instead, we recognize whether slice is inside while_loop block and pass it
as an
+ extra loop variable to avoid duplicate computation.
+
+ """
+ def __init__(self, loop_name, hash2tfnode, while_loop_name_set):
+ ExprVisitor.__init__(self)
+ self._loop_name = loop_name
+ self._hash2tfnode = hash2tfnode
+ self._while_loop_name_set = while_loop_name_set
+ self.extra_loop_var_names = set()
+
+ def _find_parent_loop_name(self, node_name):
+ """Find name of direct parent while loop."""
+ ploop_name = ""
+ name_prefix = node_name.rsplit('/', 1)[0]
+ if name_prefix.startswith("^"):
+ name_prefix = name_prefix[1:]
+ for lname in self._while_loop_name_set:
Review comment:
Added.
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